1. Field of the Invention
The present invention relates in general to a method of producing racks used in electric power steering devices, and more particularly to the method of producing the racks of a type that is meshed with both a first pinion driven by a steering wheel system and a second pinion driven by a power assisting system thereby to take part in transmitting both a steering force from a driver and an assisting force from the assisting system.
2. Description of the Related Art
One of the methods of producing racks of the electric power steering device is disclosed in Japanese Laid-open Patent Application (tokkai) 2002-154442.
The disclosed method is as follows. First, an elongate bar is prepared and the elongate bar is subjected to a hot working to form, on axially opposed portions of the bar, first rack teeth for the first pinion and second rack teeth for the second pinion respectively. Then, the first rack teeth are subjected to a cutting work. With this cutting work, undesired axial misregistration of the first rack teeth relative to the second rack teeth, which would be caused by a thermal strain produced in the first rack teeth at the time of formation of the first and second rack teeth by the hot working, is eliminated and corrected.